Computer and Controlling Method Thereof

1. A computer, comprising: a platform controller hub (PCH) having a first port and a second port; a field replaceable unit (FRU) electrically connected to the first port of the platform controller hub; a memory electrically connected to the first port of the platform controller hub; a complex programmable logic device (CPLD) electrically connected to the second port of the platform controller hub and for detecting an indicating signal of the second port to selectively generate a reset signal; and a basic input output system (BIOS) chip electrically connected to the PCH, the FRU, and the CPLD, and for selectively make the computer to reboot in a manufacturer mode or a normal mode based on the reset signal; in the manufacturer mode, the BIOS chip makes the memory inaccessible to the PCH and makes the FRU accessible to the PCH.

2. The computer in claim 1 , wherein when the computer is in the normal mode, the BIOS chip makes the FRU inaccessible to the PCH and makes the memory accessible to the PCH.

3. The computer in claim 1 , further comprises a first switch respectively electrically connected to the BIOS chip, the memory, and the PCH, and the first switch is switched by the BIOS chip between an ON state and an OFF state to determine whether a path between the first port of the PCH and the memory is conducted.

4. The computer in claim 3 , wherein when the computer is in the manufacturer mode, the first switch is in the OFF state.

5. The computer in claim 3 , wherein when the computer is in the normal mode, the first switch is in the ON state.

6. The computer in claim 1 , further comprises a second switch respectively electrically connected to the BIOS chip, the FRU, and the first port of the PCH, and the second switch is switched by the BIOS chip between an ON state and an OFF state to determine whether a path between the first port of the PCH and the FRU is conducted.

7. The computer in claim 6 , wherein when the computer is in the manufacturer mode, the second switch is in the ON state.

8. The computer in claim 6 , wherein when the computer is in the normal mode, the second switch is in the OFF state.

9. The computer in claim 1 , wherein when the PCH receives a writing request for the FRU, the computer enters the manufacturer mode and the PCH sends the indicating signal via the second port.

10. The computer in claim 1 , wherein a voltage at the second port is default high and the indicating signal is generated by temporarily pulling the voltage at the second port to low.

11. The computer in claim 1 , wherein when the BIOS chip receives the reset signal in the normal mode, the BIOS chip makes the computer rebooted in the manufacturer mode.

12. The computer in claim 1 , wherein when the BIOS chip receives the reset signal in the manufacturer mode, the BIOS chip makes the computer rebooted in the normal mode.

13. A controlling method applicable for a computer, the method comprises: in a normal mode, generating an indicating signal when a platform controller hub (PCH) receives a writing request; generating a reset signal when a complex programmable logic device (CPLD) detects the indicating signal; and when the computer is rebooted, a basic input output system (BIOS) chip makes the computer to start in a manufacturer mode; in the manufacture mode, a field replaceable unit (FRU) is accessible to the PCH and a memory is inaccessible to the PCH.

14. The method in claim 13 , further comprising: in the manufacturer mode, the CPLD adjusts the reset signal; and when the computer is rebooted, the BIOS chip makes the computer started in the normal mode according to the adjusted reset signal; wherein in the manufacturer mode, the FRU is accessible to the PCH and the memory is inaccessible to the PCH.